We are in the woods where we really wanted to create another sort of living space outside of the square footage of the home. 

I've already renovated one of the bathrooms, and I’m planning to paint the interior, update the kitchen cabinets, possibly sand the wood floors, build a fence is a corner lot and increase the rent for the room since my tenant is currently renting the entire 3-bedroom, 2-bathroom house for $800 a month.

Nobody wants a unit to sit vacant, but if you make your decisions based on fears like that they are more likely to be short sighted and make the situation worse.

Use LVP flooring, it's cheaper than installing new hard wood floors and they're more durable for longevity purposes.

Even if you use piers, they are usually concrete (which is OK for most lenders), steel or wood on concrete.

The faux wood home depot ones hold up better than the cheap plastic ones.

Henry on the Teak wood and lumber aspect.. what is the growing cycle for the hardwoods to become merch ? 

So infilling an income gap via people who can disappear just as easily as appear seems short sighted to me. 

The house is also furnished with a solid wood no spring couch, and a solid wood round dining table, and a king sized bedroom set in the master.

I actually like the cabinets from way back that were solid wood.